It is well known by those skilled in the art that pyridine compounds an be hydrogenated over catalysts comprising a Group VIII metal including iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, particularly in solvents and/or acid solutions. Rhodium is the most active Group VIII metal under acidic conditions. Nickel requires the use of high temperatures (120-175.degree. C.) and high pressures (70-150 atmospheres). Also, use of a nickel catalyst in an alcoholic solvent can result in N-alkylation (alkylation at the nitrogen (N) site) of the piperidine compound producing an undesirable N-alkylation product. The use of ruthenium in aqueous solvents is reported to require temperatures in excess of 100.degree. C. and pressures of about 70 atmospheres, but produces little if any N-alkylation product. To obtain high reactor volume productivity and the most economical and efficient process for converting pyridine compounds to piperidine compounds, it is desirable to hydrogenate pyridine compounds in the absence of any solvent or acid solution, and at the lowest possible temperature and pressure. Also, it is desirable to use a hydrogenation catalyst that is not costly and can be used to produce a sufficient quantity of piperidine compounds per quantity of pyridine compounds such that the cost of the hydrogenation catalyst is low compared to the other costs associated with the hydrogenation process. In addition, it is desirable to improve processes for the hydrogenation of pyridine compounds by minimizing the batch times for hydrogenating pyridine compounds and by minimizing the production of undesirable compounds such as heavies and n-amylamine. Heavies, as used herein, is defined to include N-alkylated piperidines and associated hydrogenolysis products and bipiperidine derivatives.